Navigation support systems of the type mentioned at the outset serve to support invasive surgical interventions by means of visualization and are basically known from prior art. Real-time video image signals may, for example, originate from an endoscope or microscope as an optical instrument. Instrument position signals may be provided by an optical or electromagnetic position detection system for detecting the location and orientation of medical instruments, e.g. pointers, endoscopes or surgical instruments. Tomography image data are typically prepared preoperatively and stored in an image database of the navigation support system.